When they nominated an inexperienced, far-left candidate for president on the Democratic ticket, did they expect white mainstream women, particularly white married women, to stick with them?As Erbe points out, while women as a whole tend to vote Democratic, white women are less likely to do so and married white women tend to vote Republican.
One could have some fun speculating on why various demographic groups vote as they do. I'd guess it mostly boils down to self-interest, to "what's in it for me."